GameMaker Studio - Basic Projectiles Video Lecture - Game Maker Tutorial

alright guys welcome back
now our ship for our side-scrolling
shooter can move around easily enough
now we need it to be able to shoot so it
can shoot our enemies slay them all
Brynn is glorious prizes and points so
in order to do this I'm probably gonna
split this into two parts first part
being just how to make your ship shoot
generally and then the second part we'll
kind of explore kind of more in depth
and sort of show the different kind of
options we have for like making it so
holding down the button will shoot over
times and I'll keep pressing in and I'd
you know change how our bullets like
move around and shoot and all that kind
of thing and so sort of you know a
slightly different approach on how we
did it last time because last time I
just kind of went through everything all
once so I'm just gonna kind of split
this down into two parts well first of
all we just cover the basics and then
second second of all for those that are
interested we we got a bit more in depth
and we add a bit of polish and change
things up a bit
so on a very basic level then we just
want to make our ship shoot every time
every time we press say I don't know
what button we should use will go with
could we'll go with the spacebar
I guess baseball works I was gonna say
shift but people tend to hate it when
you shift and it creates the the sticky
keys popup on windows you can disable
that but I know some people have a
problem with it so we'll go with a
spacebar I've already created an object
here on my obj underscore bullet which
we're going to use for shooing if you
don't know anything about objects naming
conventions or sprites like that please
refer to my very first video on game
maker basics because you really should
know all this stuff by now so and we
already have the bullet up here we have
a very very simple sprite that's just
like a little blue blue laser and I just
want to show you where I put the it's
very hard to see on but I put the the
origin of this bullet to be this bottom
center pixel here because there's only
three pixel right sprite so I'll put it
dead in the center here because if you
remember our origin decides you know the
exact coordinates
from our object on the screen so putting
it here and then place will allow us to
sort of you know make sure the bullet
isn't sort of inside our ship when when
it fires because we're going to create
the object like on top of our ship so
for the origin right to the bottom of
the Lille's of that so now we have this
object and we basically need to make a
salt every time we press spacebar we
create that object that's the very first
thing we need to do so if we go into our
object player over here and go to add
event keyboard our space there we go
space although no we don't want space
because that will do it every time we
hold the object so it would create a
laser every single frame that we're
holding spacebar and that's definitely
not what we want right now
so keyboard we want to go to a key press
even yeah that's the only one key press
space so every time you like the game
detects the the space is pressed and it
wasn't pressed the frame before meaning
you just pressed it so like it's it's
it's checking spacebar every frame is
same like zero zero zero zero zero and
then suddenly it sees one because you've
pressed the spacebar and it knows that
the frame before was you weren't
pressing the spacebar so it triggers a
press and it triggers these actions so
now if we're working we drag and drop
all we need to do is go to create
instance and we want to create this our
origin on our player should be like in
the dead center of the object I think if
I remember so x0 seems right I'll take
this relative box here so where the
coordinate is well related to the player
object so and set our object to object
bullet our X can be 0 because that means
it's going to spawn dead in the center
of our player but our Y should be
something like I think the object is 32
by 32 so if we type - 26 16 and to that
I should create the object Luiza where
we want it to be which is sort of just
at the top dead center point like at the
top here that's why we're looking to
make that so as you can see here our
origin is sick
by 16 so X 0 and -16 should be right
here and as we can see from the origin
of our bullet origin is at the bottom so
I should feel free it just sort of
sticking out of the top there so I mean
let's see exactly how that one looks so
I'll stand a movement and now if we
press space you can see I'm starting to
create bullets and you can notice the
obvious problem the bullets aren't
actually going anywhere so that's that's
what we'll look into doing next so now
that we're creating those objects what
we need to do is make it so that when
this object is created which if you've
been paying attention you already know
how to do is go to events and go to
create so on our create event when the
object is created we need to start this
object moving so using drag-and-drop
that's simple enough using move fixed
stick it direction up and say speed want
to be fairly fast I guess so eight okay
and then that's pretty much it because
we set a speed there so that speed is
gonna stay at a so every frame the
bullet is gonna move eight pixels up now
what we also want to do is make it so we
don't infinitely generate these bullets
forever and that when they pass over the
top of the screen we get rid of them
because the game doesn't need them
anymore so there are a complete waste of
memory at that point so if we go around
an event and I think it's other outside
room so this event will trigger whenever
an object not win any object even
whenever this object leaves the room
these actions will trigger and then it's
simply enough one destroy instance
that's the drag and drop anyway I'll
show you that one just because it's a
single line of code actually if we
delete that when we just go to control
code and we bring off apparently massive
execute code browser up all you need to
do here is type instance try trying to
be as quiet as possible on my mega loud
keyboard probably doesn't come across
that way but it is very difficult to be
quiet on this thing instance destroy
Open bracket close bracket because it's
a function without any any arguments to
pass over so we just close the brackets
instantly and then optionally you don't
even need that but like it's cleaner to
put a semicolon there just to tell the
game that that's the end
the line of code tick so then that
should work pretty much straight away
yep so now every time we press space
you're shooting you're shooting some
lasers and you can see they're spawning
in the right place they're moving up to
the top of the screen and then every
time they're passing over the top of the
screen they go away and they're
destroyed and that completely completely
removed from the game so yeah that's
pretty much how you do that we can
change this here we don't need to use an
action here we can use a GML instead
it's very very simple all you need to do
is delete this replace it with code that
if you remember from our movement
tutorial we just need to set our V speed
to be equal to minus 8 because you know
we're moving upwards so we're lowering
our V position or our y-coordinate sorry
so we're moving negatively in vertical
direction
so we want minus 8 and then that's
exactly pretty much the same as what we
just did a second ago and so on
semicolon there as well okay a pile
exactly the same no change so yep that's
pretty much pretty much everything you
need to know that oh oh in this one as
well we can convert this to GML really
quickly as well creating the instance
again it's just one line of code
instance underscore create you can find
all of these functions just by hitting
them I'll show you this now actually if
you just hit f1 you'll bring up the help
menu if you go like into the index for
example like every single line of code
is like every function and everything
like that is in here all sorts of
information you get from here when
you're learning the coding and stuff so
I mean you can you can find all of these
exact all of these little functions and
things that like you obviously I'm just
sort of pulling out Noah at the moment
you can find them in the whole menu so
instance create bracket and then we just
type in the coordinates it's already
assuming it to be no it's not even what
am I talking about I was gonna say it's
assuming it to be relative but it's not
what we want to do to make it relative
so obviously if we type something like
50/50 in here that would put it 50/50 on
the screen so what do want it to be
relative to our objects but we don't
like tick a flag or anything for
we just reference the coordinates of the
object so we type X which is equal to
the cool the x-coordinate of our player
object because this is the object to it
bringing the kodan so we want it to be
our X as we discussed before and we
wanted it to be our y coordinate minus
16 so now as you might have guessed Y
minus 16 and then the object we want to
create is obj underscore call it close
bracket semicolon and that's that's
simply how you do that then we have five
press space exactly the same shooting so
yeah in part two we'll go over sort of
some more tricks for that because at the
moment we're just having we're having to
press space every time the fire so I'll
go over how to make us so you can hold
down spacebar to like continuously shoot
like every like 10 frames or something
like that I'm going to show you how to
like I just the sort of pattern the way
it shoots make the bullets wave around
if you really needed them to or how to
shoot at a specific location you know
all those kind of things we'll
investigate in more detail in part two
of the shooting tutorial which will be
shooting advanced I guess and this that
is pretty much shooting basics so yeah I
hope you enjoyed that I hope you learned
something from it and I'll catch you
next time guys